Familiarization Trial Research Articles

Effect of caffeine on RPE and perceptions of pain, arousal, and pleasure/displeasure during a cycling time trial in endurance trained and active men

Caffeine has been reported to alter perceptions of exertion, muscle pain, and mood, yet the majority of existing data were obtained in resting volunteers or during steady-state exercise. The primary aim of this study was to examine the effects of caffeine on rating of perceived exertion (RPE) and perceptions of leg pain, arousal, and pleasure/displeasure during a simulated cycling time trial. Endurance-trained (n=8, VO2max=57.5±3.9mL/kg/min) and active (n=8, VO2max=46.5±6.3mL/kg/min) men initially completed two familiarization trials separated by at least 48h. Over the next three trials, they completed a 10km time trial preceded by ingestion of drinks containing caffeine (5mg/kg ingested on 2 separate days) or placebo. Treatments were ingested using a single-blind, crossover design, and participants were deceived as to the content of all drinks. During exercise, RPE (6–20 scale), leg pain (0–10 scale), arousal (Felt Arousal Scale), and pleasure/displeasure (Feeling Scale) were recorded using various categorical scales. Repeated measures analysis of variance was used to assess differences in all variables across time and treatments, with fitness level used as a between-subjects variable. Pleasure/displeasure was altered (p<0.05, partial eta-squared (η2)=0.23) with caffeine compared to placebo, although leg pain, RPE, and arousal were similar (p>0.05) across treatments. Caffeine increased (p<0.05, η2=0.27) cycling performance by 0.3–2.0% versus placebo, with no effect (p>0.05) of fitness level. Only in trained men; however, was there a significant caffeine-mediated improvement in cycling performance, which was consequent with diminished mood in trained and improved mood in active individuals.

Increases in cycling performance in response to caffeine ingestion are repeatable

The primary aim of this study was to determine the repeatability of caffeine's ergogenic effects on cycling performance. It was hypothesized that improvements in performance would be similar when caffeine was ingested on 2 separate days. Nine endurance-trained men and women (mean age and maximal oxygen uptake, 27.4 ± 5.9 years and 57.5 ± 3.9 mL kg⁻¹ min⁻¹) initially completed 2 familiarization trials. During 3 subsequent sessions separated by at least 48 hours, the subjects completed a 10-km cycling time trial preceded by ingestion of a drink containing caffeine (5 mg/kg) or placebo. Treatments were ingested using a randomized, single-blind, crossover design, and the subjects were deceived as to the specific content of all drinks. During exercise, heart rate, rating of perceived exertion, and time were recorded every 1.6 km. Repeated-measures analysis of variance was used to compare the differences in variables across distance and treatment. In both caffeine trials, caffeine increased (P = .02) cycling performance by 1.6% and 1.9% vs placebo (16.98 ± 0.96 and 16.92 ± 0.97 minutes with caffeine vs 17.25 ± 0.96 minutes in placebo), and 7 of 9 subjects revealed improved performance. The mean performance improvement in the caffeine trials was similar (P = .35; -0.27 and -0.32 minutes, respectively) across days. Heart rate during exercise was higher (P b .001) with caffeine vs placebo, although the rating of perceived exertion was similar (P = .65). Data reveal that caffeine's ergogenic effects on cycling performance are repeatable across days, yet some individuals did not exhibit improved performance with caffeine.

Effect of Dilute CHO Beverages on Performance in Cool and Warm Environments

The efficacy of drinks containing low concentrations of CHO (2%-6%) on physical performance in cool and warm environments was evaluated. In two separate but related studies, 24 healthy males completed a familiarization trial and four trials to volitional exhaustion (TTE) at 70% VO2max in cool conditions (10°C, n = 12) or 60% VO2max in a warm environment (30°C, n = 12). Subjects ingested 0%, 2%, 4%, or 6% CHO solutions (sucrose, glucose, and fructose in a ratio of 50:25:25) immediately before exercise and every 10 min during exercise. TTE in 10°C was 102.6 ± 33.9, 109.2 ± 33.9, 121.0 ± 25.7, and 122.4 ± 29.9 min in the 0%, 2%, 4%, and 6% trials, respectively (P = 0.012). Compared with the 0% trial, TTE was longer in the 4% (P = 0.032, effect size (ES) = 0.72) and 6% (P = 0.044, ES = 0.66) trials. In addition, TTE was longer in the 6% trial than in the 2% trial (P = 0.025). TTE was also significantly influenced by drink CHO content at 30°C (0% = 94.5 ± 24.5 min, 2% = 104.1 ± 20.1 min, 4% = 105.5 ± 26.7 min, 6% = 112.0 ± 28.7 min; P = 0.046). No differences in TTE were apparent between the 0% and the 2% or 4% trials, but TTE was longer in the 6% trial compared with the placebo (P = 0.045, ES = 0.62). HR, core temperature, or rates of substrate oxidation were not affected by drink CHO content. These results demonstrate significant improvements in exercise capacity over the placebo trial when 4% and 6% CHO solutions were ingested at 10°C and a 6% CHO drink was ingested at 30°C.

Validity and Reliability of Agility Tests in Junior Australian Football Players

Young, W, Farrow, D, Pyne, D, McGregor, W, and Handke, T. Validity and reliability of agility tests in junior Australian football players. J Strength Cond Res 25(12): 3399-3403, 2011-The importance of sport-specific stimuli in reactive agility tests (RATs) compared to other agility tests is not known. The purpose of this research was to determine the validity and reliability of agility tests. Fifty junior Australian football players aged 15-17 years, members of either an elite junior squad (n = 35) or a secondary school team (n = 15), were assessed on a new RAT that involved a change of direction sprint in response to the movements of an attacking player projected in life size on a screen. These players also underwent the planned Australian Football League agility test, and a subgroup (n = 13) underwent a test requiring a change of direction in response to a left or right arrow stimulus. The elite players were significantly better than the school group players on the RAT (2.81 ± 0.08 seconds, 3.07 ± 0.12 seconds; difference 8.5%) but not in the arrow stimulus test or planned agility test. The data were log transformed and the reliability of the new RAT estimated using typical error (TE) expressed as a coefficient of variation. The TE for the RAT was 2.7% (2.0-4.3, 90% confidence interval) or 0.07 seconds (0.5-1.0), with an intraclass correlation coefficient (ICC) of 0.33. For the test using the arrow stimulus, the TE was 3.4% (2.4-6.2), 0.09 (0.06-0.15) seconds, and ICC was 0.10. The sport-specific stimulus provided by the new RAT is a crucial component of an agility test; however, adoption of the new RAT for routine testing is likely to require more accessible equipment and several familiarization trials to improve its reliability.

Ergogenic Effects of Caffeine on Simulated Time-Trial Performance Are Independent of Fitness Level

Background: The primary aim of this study was to compare the ergogenic effects of caffeine on cycling performance in endurance-trained and recreationally active participants. Methods: Endurance-trained [n=8, VO2max=57.5±3.9 mL/(kg·min)] and active [n=8, VO2max=46.5±6.3 mL/(kg·min)] participants initially completed two familiarization trials separated by at least 48 hours. Over the next three trials, they completed a 10 km cycling time trial preceded by ingestion of drinks containing caffeine (5 mg/kg ingested on 2 separate days) or placebo. Treatments were ingested using a single-blind, crossover design, and participants were deceived as to the content of all drinks. During exercise, heart rate (HR), rating of perceived exertion (RPE), and time were recorded every 1.6 km. Repeated measures analysis of variance was used to assess differences in cycling time, HR, and RPE between treatments, with fitness level used as a between-subjects variable. Results: Caffeine increased (p<0.05) cycling performance by 0.3%–2.0% versus placebo, with no effect (p>0.05) of fitness level. Magnitude of performance improvement in both caffeine trials (−0.21 and −0.23 minutes, respectively) was similar versus placebo. Compared with placebo, exercise HR was higher (p<0.05) with caffeine, although RPE was similar (p>0.05) across treatments. Conclusions: In active men of varying fitness, data reveal a small caffeine-mediated improvement in cycling performance that was similar in magnitude.

Perirhinal cortex lesions uncover subsidiary systems in the rat for the detection of novel and familiar objects

The present study compared the impact of perirhinal cortex lesions on tests of object recognition. Object recognition was tested directly by looking at the preferential exploration of novel objects over simultaneously presented familiar objects. Object recognition was also tested indirectly by presenting just novel objects or just familiar objects, and recording exploration levels. Rats with perirhinal cortex lesions were severely impaired at discriminating a novel object from a simultaneously presented familiar object (direct test), yet displayed normal levels of exploration to novel objects presented on their own and showed normal declines in exploration times for familiar objects that were repeatedly presented (indirect tests). This effective reduction in the exploration of familiar objects after perirhinal cortex lesions points to the sparing of some recognition mechanisms. This possibility led us to determine whether rats with perirhinal cortex lesions can overcome their preferential exploration deficits when given multiple object familiarisation trials prior to that same (familiar) object being paired with a novel object. It was found that after multiple familiarisation trials, objects could now successfully be recognised as familiar by rats with perirhinal cortex lesions, both following a 90-min delay (the longest delay tested) and when object recognition was tested in the dark after familiarisation trials in the light. These latter findings reveal: (i) the presumed recruitment of other regions to solve recognition memory problems in the absence of perirhinal cortex tissue; and (ii) that these additional recognition mechanisms require more familiarisation trials than perirhinal-based recognition mechanisms.

Effect of cold acclimatization on exercise economy in the cold

We sought to determine if cold acclimatized men display higher economy (i.e. lower oxygen consumption at a given workload) during graded cycle ergometry in the cold (5°C). After completing a familiarization trial 1 week prior, five cold weather athletes (CWA) and eight physically active men (NON) underwent graded exercise tests to volitional fatigue in 5°C. The protocol always started at 60 W and increased by 20 W each minute. Oxygen consumption (VO(2)), respiration rate (RR), tidal volume (TV), and respiratory exchange ratio (RER) were determined via open circuit spirometry. Individuals were matched for body size and minutes of weekly physical activity. Repeated measures analyses of variance were conducted across time (workload) and cold acclimatization was entered as a between subjects factor. VO(2) peak was not different between groups but CWA had lower VO(2) at 60 and 240 W. CWA also had lower RR at 180 and 260 W as well as lower RER at 240 and 260 W. At submaximal workloads, cold acclimatized men have higher exercise economy than non-acclimatized men. This could have implications for those who work in this context.

Effect of ascending vs. descending velocity order on peak torque during isokinetic testing in males

The vast majority of previous research with isokinetic machines has used only ascending or random velocity sets during testing. The purpose of this study was to investigate the effect velocity order (ascending vs. descending order) had on peak torque of knee extension during isokinetic testing and to examine the differences in peak torque in collegiate and recreational athletes. Thirty healthy, college aged males (15 collegiat e athletes (CA): mean Age 20.27 yrs, Ht 178.99 cm, Mass 85.00 kgs and 15 recreational athletes (RA): Age 21.2 yrs, Ht 183.39 cm, Mass 89.06 kgs) performed two familiarization trials and four randomly assigned experimental trials. Subjects performed four knee extension repetitions at five velocities in eithe r ascending (60, 120, 180, 240, and 300 � /sec) or descending (300, 240, 180, 120, 60 � /sec) order. There was no significant ( p < 0.05) difference between the order of velocities and peak torque or between CA and RA groups. Although not statistically significant, RA produced greater peak torque than CA. This may be a result of numerous RAs in this study being former collegiate athletes. In conclusion, the order of velocities may not be pertinent when establishing a protocol for testing peak torque of the knee extensors in healthy college-aged males.

The Effect Of Acupuncture Treatment On The Recovery From Delayed Onset Of Muscle Soreness(DOMS)

Delayed Onset of Muscle Soreness (DOMS) is attributed to novel activity, overexertion, and eccentric muscle loading. It is associated with impaired strength, localized swelling, discomfort, and reduced range of motion. DOMS treatments traditionally include ice, heat, massage, rest, and anti-inflammatory drugs. PURPOSE: To evaluate the effect of a single acupuncture treatment on the severity and duration DOMS. METHODS: Twenty nine healthy subjects(mean age 23 yr.)volunteered to perform a familiarization trial of 6 RM dumbbell bicep curl @ a 3-1-3 cadence, water immersion for arm volume (Vol), and a Pain Rating Scale (PRS), cumulatively labeled as the evaluation (E). A minimum of five days following the familiarization trial, Pre DOMS E was obtained followed by the DOMS induction treatment (bicep curl with concentric failure @ the 6 RM load and eccentric failure @ 6RM load plus 40%). Post DOMS E was obtained within 15 minutes post induction. Subjects were randomly assigned to either treatment group Acupuncture (A) or Sham (S) and at 24 hours post induction, the pre-treatment E and the post-treatment E were administered. Five sites (head, shoulder (2), elbow, hand, and asci (3 at the point of maximal DOMS) were used for needle insertion. Trial A used deep insertion at acupoint sites; Trial S used superficial needle insertions that were in proximity to, but not at the acupoint sites. At 48, 72, and 96 hrs post DOMS induction E were obtained, respectively. Statistical analysis by ANOVA was applied to these data (p<.05). RESULTS: The following data were obtained for Trial A and S, respectively:TableNo significant differences were found between treatments. CONCLUSION: The use of a single acupuncture treatment does not alter the time course of DOMS recovery.

Effects of red bull energy drink on repeated sprint performance in women athletes

Energy drinks are frequently consumed by athletes prior to competition to improve performance. This study examined the effect of Red Bull™ on repeated sprint performance in women athletes. Fifteen collegiate soccer players participated, with mean age, height, and body mass equal to 19.5±1.1 year, 168.4±5.8 cm, and 63.4±6.1 kg, respectively. After performing a familiarization trial, subjects performed three sets of eight bouts of the modified t test after ingestion of 255 mL of placebo or Red Bull 1 h pre-exercise in a randomized, placebo-controlled crossover design. Throughout testing, sprint time, heart rate (HR), and rating of perceived exertion (RPE) were continuously obtained. Repeated measures analysis of variance was used to examine differences in variables between drink conditions. Across athletes, t test time ranged from 10.4 to 12.7 s. Mean sprint time was similar (p>0.05) between Red Bull (11.31±0.61 s) and placebo (11.35±0.61 s). HR and RPE increased (p<0.05) during the bouts, but there was no effect (p>0.05) of Red Bull on either variable versus placebo. Findings indicate that 255 mL of Red Bull containing 1.3 mg/kg of caffeine and 1 g of taurine does not alter repeated sprint performance, RPE, or HR in women athletes versus placebo. One serving of this energy drink provides no ergogenic benefit for women athletes engaging in sprint-based exercise.

Cold acclimatized men have higher economy during incremental exercise in the cold

The purpose of the current investigation was to determine if cold acclimatized men display higher economy (i.e. lower oxygen consumption at a given workload) during graded cycle ergometry in the cold. After completing a familiarization trial, five cold weather athletes (CWA) and eight physically active men (NON) underwent graded exercise tests to volitional fatigue in 5°C. The protocol always started at 60 watts and increased by 20 watts each minute. Oxygen consumption (VO2), respiration rate (RR), tidal volume (TV), and respiratory exchange ratio (RER) were determined via open circuit spirometry. Individuals were purposely matched for body size and aerobic capacity was not different between groups at exhaustion. Generalized estimation equations were used to assess differences across time (workload at each minute) and group (CWA, NON). As expected, all dependent variables revealed a main effect for time. VO2, RR, and RER also showed a main effect for group, whereby CWA had lower parameters regardless of time. A group by time interaction was found for all dependent variables. Large within-group variability prevented statistical significance at any specific workload. As demonstrated by the interaction effect, both workload and cold-acclimatization have an effect on the ventilatory response to incremental cycle ergometry in the cold. This could have implications for those who work in the cold.

Amodal completion in infants: Straight continuity versus symmetry1

A visual pattern's orientation influences how adults amodally complete that pattern. We examined whether this is also the case with infants using Markovich's pattern, consisting of a black polygon partially occluded by a gray disc, which is completed as either a vertically symmetrical hexagon or as a pentagon, depending on the pattern's orientation. Our experiment consisted of two prefamiliarization test trials, six familiarization trials, and two postfamiliarization test trials. In the familiarization trials, two identical Markovich patterns, upright or slanted, were presented to 7–8-month-old infants (N = 28) side by side on a CRT monitor. In the pre- and postfamiliarization test trials, a pentagon and a hexagon were presented side by side. Infants looked longer at the hexagon than at the pentagon in the postfamiliarization test trials. This suggests that infants completed the pattern as a pentagon regardless of the pattern's orientation. This lack of an orientation effect suggests that infants do not use the figure's symmetry as a guiding principle for amodal completion.

Explosive Leg Press Stretch-Shortening Potentiation

The importance of understanding how the stretch-shortening cycle (SSC) may enhance muscle performance over concentric-only (CO) contractions has great relevance to sport scientists, coaches, and athletes. Potentiation is the enhancement that occurs in the concentric phase of the SSC as compared to performing concentric-only contractions (contractions with no immediate preceding eccentric contractions). PURPOSE: To determine ballistic leg press potentiation of force, acceleration, velocity, and power at six leg press sled time intervals across the concentric range of motion (ROM) and at ten time intervals across the initial 200 ms of the concentric phase of contraction. We also sought to determine relationships between specific potentiation variables and the time of the amortization phase and eccentric force during the last 100 ms of the eccentric phase of the SSC. METHODS: Twenty-one male competitive distance runners (age: 31 ± 5 yrs; weight: 80 ± 11 kg) performed SSC and CO leg press ballistic throws with a load of 150% bodyweight on a 35 degree angle leg press machine. The machine connected to a cable-extension linear position transducer that was interfaced with a data acquisition system utilizing custom software. After familiarization, warm-ups, and practice trials subjects performed 3 SSC and 3 CO leg press ballistic throws with a large amplitude concentric ROM at the knee from 90 to 0 degrees. Test-retest evaluations of muscle performance variables for this study have a coefficient of variation ranging from 1.7% to 4.3%. RESULTS: Across the full concentric ROM, differences from zero (p<0.05) existed with 1) potentiated mean force and acceleration only at the first 1/6th time interval over the concentric phase, and 2) potentiated mean velocity and power at all leg press time intervals over the entire concentric phase with the exception of power over the last 1/6 time interval (closest to full knee extension). Across the initial 200ms of the concentric phase, differences from zero (p<0.05) existed with 1) potentiated mean force and acceleration up until the time intervals greater than 160 ms, and 2) potentiated mean velocity and power for all time intervals over the first 200ms of the concentric phase. There were significant correlations between eccentric mean force measured during the last 100ms of the eccentric phase and potentiated average mean force during the initial 200ms of the concentric phase (r = 0.44, p<0.05) and potentiated average mean power across the full concentric ROM (r = 0.62, p < 0.01). CONCLUSIONS: Findings indicate large amplitude SSC leg press ballistic throws potentiate mean force, acceleration, velocity, and power early in the concentric ROM, and that potentiated mean velocity and power are conserved throughout the full concentric ROM with the exception of power at the very end of the range. Eccentric mean force measured during the last 100ms of the stretching phase is positively related to potentiated average mean force during the initial 200ms of the concentric phase and potentiated average mean power across the full concentric ROM. Practical Applications: To facilitate positive effects on potentiated concentric force and power during large amplitude SSC movements like an explosive leg press exercise, it may be beneficial to specifically train to improve force late in the eccentric phase of the SSC.

Failure of Glycine-Arginine-α-Ketoisocaproic Acid to Improve High-Intensity Exercise Performance in Trained Cyclists

Oral supplementation with glycine-arginine-α-ketoisocaproic acid (GAKIC) has previously been shown to improve exhaustive high-intensity exercise performance. There are no controlled studies involving GAKIC supplementation in well-trained subjects. The aim of the current study was to examine the effects of GAKIC supplementation on fatigue during high-intensity, repeated cycle sprints in trained cyclists. After at least 2 familiarization trials, 10 well-trained male cyclists completed 2 supramaximal sprint tests each involving 10 sprints of 10 s separated by 50-s rest intervals on an electrically braked cycle ergometer. Subjects ingested 11.2 g of GAKIC or placebo (Pl) during a period of 45 min before the 2 experimental trials, administered in a randomized and double-blind fashion. Peak power declined from the 1st sprint (M ± SD; Pl 1,332 ± 307 W, GAKIC 1,367 ± 342 W) to the 10th sprint (Pl 1,091 ± 229 W, GAKIC 1,061 ± 272 W) and did not differ between conditions (p = .88). Mean power declined from the 1st sprint (Pl 892 ± 151 W, GAKIC 892 ± 153 W) to the 10th sprint (Pl 766 ± 120 W, GAKIC 752 ± 138 W) and did not differ between conditions (p = .96). The fatigue index remained at ~38% throughout the series of sprints and did not differ between conditions (p = .99). Heart rate and ratings of perceived exertion increased from the 1st sprint to the 10th sprint and did not differ between conditions (p = .11 and p = .83, respectively). In contrast to previous studies in untrained individuals, these results suggest that GAKIC has no ergogenic effect on repeated bouts of high-intensity exercise in trained individuals.

Cooling the Neck Region During Exercise in the Heat

Cooling the neck region can improve the ability to exercise in a hot environment. It might improve performance by dampening the perceived level of thermal strain, allowing individuals to override inhibitory signals. To investigate whether the enhanced ability to exercise in a hot environment observed when cooling the neck region occurs because of dampening the perceived level of thermal strain experienced and the subsequent overriding of inhibitory signals. Crossover study. Walk-in environmental chamber. Eight endurance-trained, nonacclimated men (age = 26 ± 2 years, height = 1.79 ± 0.04 m, mass = 77.0 ± 6.2 kg, maximal oxygen uptake [V˙O(2max)] = 56.2 ± 9.2 mL·kg(-1)·min(-1)) participated. Participants completed 4 running tests at approximately 70% V˙O(2max) to volitional exhaustion: 2 familiarization trials followed by 2 experimental trials (cooling collar [CC] and no collar [NC]). Trials were separated by 7 days. Familiarization and NC trials were performed without a collar and used to assess the test variability. Time to volitional exhaustion, heart rate, rectal temperature, neck skin temperature, rating of perceived exertion, thermal sensation, and feeling scale (pleasure/displeasure) were measured. Time to volitional exhaustion was increased by 13.5% ± 3.8% (CC = 43.15 ± 12.82 minutes, NC = 38.20 ± 11.70 minutes; t(7) = 9.923, P < .001) with the CC, which reduced mean neck skin temperature throughout the test (P < .001). Participants terminated exercise at identical levels of perceived exertion, thermal sensation, and feeling scale, but the CC enabled participants to tolerate higher rectal temperatures (CC = 39.61°C ± 0.45°C, NC = 39.18°C ± 0.7°C; t(7) = -3.217, P = .02) and heart rates (CC = 181 ± 6 beats/min, NC = 178 ± 9 beats/min; t(7) = -2.664, P = .03) at the point of termination. Cooling the neck increased the time taken to reach volitional exhaustion by dampening the perceived levels of thermal strain.

A Computational Model for Cued Infant Learning

A Computational Model for Cued Infant Learning

A Novel Field Test to Determine Critical Speed

The aim of this study was to assess the reliability of a novel field test of critical running speed (CS). Ten trained male distance runners completed a familiarisation trial plus three separate experimental trials on a standard 400 m athletics track. Each trial consisted of three distances (1200, 2400 and 3600 metres) that were selected to produce finishing times in the region of 3, 7 and 12 minutes respectively. Participants were instructed to cover the set distance in the fastest time possible. Participants rested for 30 minutes between efforts. Data were modelled using the linear distance-time model, described by the equation: d = (CS x t) + ARC, where: d = distance run (m), t = running time (s), and ARC = anaerobic running capacity (m). Results demonstrated a coefficient of variation (CV) of 2.0% (95% confidence limit (95% CL): 1.4–3.8%) for trials 2–1 and 1.3% (95% CL: 0.9–2.4%) for trials 3–2. There was no significant difference in CS (m·s -1 ) across trials (P<0.05). The limits of agreement were ±0.27m·s -1 of the measure for trials 2–1 and ±0.18 m·s -1 for trials 3–2. ARC proved to be less reliable with a group CV of 18.4% (95% CL: 13.5– 39.9%) for trials 2–1 and 9.8% (95% CL: 7.0–19.6%) for trials 3–2. Although the assessment of ARC is less reliable, CV data are similar to those reported previously during laboratory-based testing.

Infants learn about objects from statistics and people.

In laboratory experiments, infants are sensitive to patterns of visual features that co-occur (e.g., Fiser & Aslin, 2002). Once infants learn the statistical regularities, however, what do they do with that knowledge? Moreover, which patterns do infants learn in the cluttered world outside of the laboratory? Across 4 experiments, we show that 9-month-olds use this sensitivity to make inferences about object properties. In Experiment 1, 9-month-old infants expected co-occurring visual features to remain fused (i.e., infants looked longer when co-occurring features split apart than when they stayed together). Forming such expectations can help identify integral object parts for object individuation, recognition, and categorization. In Experiment 2, we increased the task difficulty by presenting the test stimuli simultaneously with a different spatial layout from the familiarization trials to provide a more ecologically valid condition. Infants did not make similar inferences in this more distracting test condition. However, Experiment 3 showed that a social cue did allow inferences in this more difficult test condition, and Experiment 4 showed that social cues helped infants choose patterns among distractor patterns during learning as well as during test. These findings suggest that infants can use feature co-occurrence to learn about objects and that social cues shape such foundational learning in distraction-filled environments.

Familiarization, Reliability, and Evaluation of a Multiple Sprint Running Test Using Self-Selected Recovery Periods

The aims of the present study were to investigate the process of self-selected recovery in a multiple sprint test with a view to using self-selected recovery time as a means of reliably quantifying an individual's ability to resist fatigue in this type of exercise. Twenty physically active exercise science students (means ± SD for age, height, body mass, body fat, and VO2max of the subjects were 21 ± 2 yr, 1.79 ± 0.09 m, 83.7 ± 10.8 kg, 16.6 ± 3.9%, and 52.7 ± 7.2 ml·kg·min, respectively) completed 4 trials of a 12 × 30 m multiple sprint running test under the instruction that they should allow sufficient recovery time between sprints to enable maximal sprint performance to be maintained throughout each trial. Mean recovery times across the 4 trials were 73.9 ± 24.7, 82.3 ± 23.8, 77.6 ± 19.1, and 77.5 ± 13.9 seconds, respectively, with variability across the first 3 trials considered evidence of learning effects. Test-retest reliability across trials 3 to 4 revealed a good level of reliability as evidenced by a coefficient of variation of 11.1% (95% likely range: 8.0-18.1%) and an intraclass correlation coefficient of 0.76 (95% likely range: 0.40-0.91). Despite no change in sprint performance throughout the trials, ratings of perceived exertion increased progressively and significantly (p < 0.001) from a value of 10 ± 2 after sprint 3 to 14 ± 2 after sprint 12. The correlation between relative VO2max and mean recovery time was 0.14 (95% likely range: -0.37-0.58). The results of the present study show that after the completion of 2 familiarization trials, the ability to maintain sprinting performance in a series of repeated sprints can be self-regulated by an athlete to a high degree of accuracy without the need for external timepieces.

The effect of water immersion on the recovery of team-sport-specific exercise

Introduction: The purpose of the present study was to examine the effects of two hydrotherapy techniques, cold water immersion (CWI) and contrast-water therapy (CWT), on the recovery of team-sport-specific exercise tests following muscle-damaging exercise. Methods: Seven male, team-sport players (mean±SD age: 21±2 y, body mass:76.8±7.2 kg) completed a preliminary familiarisation trial for three team-sport-specific exercise tests (TESTS), which included an all-out 30-m sprint test, two agility T-tests (left and right) and a vertical jump test. Three experimental trials were subsequently carried out, each separated by one week, using a counter-balanced cross-over design. On each visit a resting fingertip blood sample and a rating of perceived muscle soreness (PMS) was collected. Participants then performed the TESTS, followed by a 5-min rest period. A repeated sprint exercise (RSE) protocol was then performed to induce muscle damage, which comprised of 15 × 30-m sprints with a 10-m deceleration zone. Sprints were separated by 1 min. A second fingertip blood sample and PMS score was collected immediately after the RSE and a second set of TESTS were performed 10 min after the RSE. Participants then received either CWI, CWT or no water immersion (CON). The next day (24–28 h later) a final fingertip blood sample and PMS score was collected and a final set of TESTS were completed. Results and conclusion: There were no changes in plasma CK over time and no significant interaction effects between the three intervention groups (P > 0.05). The PMS increased from baseline to 24–28 h in the CON group (P 0.05). The PMS was significantly higher for CON compared with CWT after 24–28 h (P 0.05). There were no significant differences in performance during the TESTS between the three intervention groups across any of the three time points (pre RSE, post RSE or after 24–28 h; P > 0.05). These data suggest that the RSE may not have induced sufficient muscle damage to increase plasma CK levels, which may explain why the recovery interventions did not have a significant effect on performance of the TESTS. However, the differences in PMS changes indicate that hydrotherapy may be effective in suppressing the perception of muscle soreness when biochemical and performance markers are unchanged.